This invention relates to a gear system and is particularly concerned with a gear system such as a planetary gear system wherein a plurality of gears are in meshing engagement with the central gear, transmission power being equally divided into said plurality of gears.
As an example of such gear system, there has hitherto been known a speed reducing mechanism for use in connection with a geared motor as shown in FIG. 1. In such a speed reducing mechanism, an input shaft 2 supported in a motor casing 1 is operatively associated with an external gear 3 which serves as a sun gear. Three planetary gears 5 are disposed between the external gear 3 and a stationary gear 4 for meshing purposes. Associated operatively with an output shaft 7 is a carrier 6 adapted to rotatably support the planetary gears 5. Now, in such a planetary gear mechanism, assuming that central distances L1 between the respective adjacent planetary gears are exactly coincident with each other and central distances L2 between the external gear 3 and the adjacent planetary gears are also exactly coincident with each other as shown in FIG. 2, the planetary gears are disposed in equal spaced relationship with each other. Therefore, load is evenly applied to the respective planetary gears 5 provided that the respective gears 3, 4 and 5 have no error. Thus, these gears 3, 4 and 5 may be operated as positively as expected. In practice, however, coincidence of each of the central distances L1 and L2 is hardly accomplished. Furthermore, bearing portions of the respective planetary gears 5 and the gears 3, 4 and 5 are naturally never free of errors. As a consequence, even application of the load is hardly effected and power is not equally divided. In addition, there is a disadvantage that noises occur due to vibrations of the whole speed reducing mechanism.